The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Image guided medical and surgical procedures utilize patient images obtained prior to or during a medical procedure to guide a physician performing the procedure. Recent advances in imaging technology, especially in imaging technologies that produce highly-detailed, two, three, and four dimensional images, such as computed tomography (CT), magnetic resonance imaging (MRI), fluoroscopic imaging (such as with a C-arm device), positron emission tomography (PET), and ultrasound imaging (US) has increased the interest in navigated medical procedures.
Generally, during a navigated procedure, images are acquired by a suitable imaging device for later display on a workstation. The navigation system tracks the patient, instruments and other devices in the surgical field or patient space. These tracked devices are then displayed relative to the image data on the workstation in image space. In order to track the patient, instruments and other devices, the patient, instruments and other devices can be equipped with tracking devices.
Generally, tracking devices are coupled to an exterior surface of the instrument, and can provide the surgeon, via the tracking system, an accurate depiction of the location of that instrument in the patient space. In cases where a first instrument moves within a second instrument, however, it can be difficult to accurately determine the location of the distal most end of the instrument assembly, as depending upon the movement of the first instrument within the second instrument, either the first instrument or the second instrument can form the distal most end. For example, in the case of a drill bit that moves within a drill guide, depending upon the advancement of the drill bit, the end of the drill guide or the end of the drill bit can form the distal most end of the instrument assembly.